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Chapter 4 Part B Tissue: The Living Fabric © Annie Leibovitz/Contact Press Images © 2016 Pearson Education, Inc. PowerPoint® Lecture Slides prepared by Karen Dunbar Kareiva Ivy Tech Community College 4.3 Connective Tissue • Connective tissue is the most abundant and widely distributed of primary tissues • Major functions: binding and support, protecting, insulating, storing reserve fuel, and transporting substances (blood) • Four main classes – Connective tissue proper – Cartilage – Bone – Blood © 2016 Pearson Education, Inc. Table 4.1-1 Comparison of Classes of Connective Tissues © 2016 Pearson Education, Inc. Table 4.1-2 Comparison of Classes of Connective Tissues (continued) © 2016 Pearson Education, Inc. Common Characteristics of Connective Tissue • Three characteristics make connective tissues different from other primary tissues: – All have common embryonic origin: all arise from mesenchyme tissue as their tissue of origin – Have varying degrees of vascularity (cartilage is avascular, bone is highly vascularized) – Cells are suspended/embedded in extracellular matrix (ECM) (protein-sugar mesh) • Matrix supports cells so they can bear weight, withstand tension, endure abuse © 2016 Pearson Education, Inc. Structural Elements of Connective Tissue • All connective tissues have three main elements – Ground substance – Fibers – Cells • The first two elements (ground substance and fibers) together make up the extracellular matrix – Composition and arrangement of these three elements vary considerably in different types of connective tissues © 2016 Pearson Education, Inc. Structural Elements of Connective Tissue (cont.) • Ground substance – Unstructured gel-like material that fills space between cells • Medium through which solutes diffuse between blood capillaries and cells – Components • Interstitial fluid • Cell adhesion proteins (“glue” for attachment) • Proteoglycans (sugar proteins), made up of protein core + large polysaccharides – Example: chrondroitin sulfate and hyaluronic acid • Water also is trapped in varying amounts, affecting viscosity of ground substance © 2016 Pearson Education, Inc. Structural Elements of Connective Tissue (cont.) • Connective tissue fibers • Three types of fibers provide support – Collagen • Strongest and most abundant type • Tough; provides high tensile strength – Elastic fibers • Networks of long, thin, elastin fibers that allow for stretch and recoil – Reticular • Short, fine, highly branched collagenous fibers (different chemistry and form from collagen fibers) • Branching forms networks that offer more “give” © 2016 Pearson Education, Inc. Structural Elements of Connective Tissue (cont.) • Cells – “Blast” cells • Immature form of cell that actively secretes ground substance and ECM fibers • Fibroblasts found in connective tissue proper • Chondroblasts found in cartilage • Osteoblasts found in bone • Hematopoietic stem cells in bone marrow – “Cyte” cells • Mature, less active form of “blast” cell that now becomes part of and helps maintain health of matrix © 2016 Pearson Education, Inc. Structural Elements of Connective Tissue (cont.) • Other cell types in connective tissues – Fat cells • Store nutrients – White blood cells • Neutrophils, eosinophils, lymphocytes • Tissue response to injury – Mast cells • Initiate local inflammatory response against foreign microorganisms they detect – Macrophages • Phagocytic cells that “eat” dead cells, microorganisms; function in immune system © 2016 Pearson Education, Inc. Figure 4.7 Areolar connective tissue: A prototype (model) connective tissue. Cell types Extracellular matrix Ground substance Macrophage Fibers • Collagen fiber • Elastic fiber • Reticular fiber Fibroblast Lymphocyte Fat cell Mast cell Neutrophil © 2016 Pearson Education, Inc. Capillary Types of Connective Tissues • There are four main classes of connective tissue: – Connective tissue proper – Cartilage – Bone – Blood © 2016 Pearson Education, Inc. Types of Connective Tissues (cont.) • Connective tissue proper – Consists of all connective tissues except bone, cartilage, and blood – Two subclasses • CT proper: loose connective tissues – Areolar – Adipose – Reticular • CT proper: dense connective tissues – Dense regular – Dense irregular – Elastic © 2016 Pearson Education, Inc. Types of Connective Tissues (cont.) • CT proper: loose connective tissues – Areolar connective tissue • • • • Most widely distributed CT Supports and binds other tissues Universal packing material between other tissues Contains fibroblasts that secrete loose arrangement of mostly collagen fibers • Loose fibers allow for increased ground substance, which can act as water reservoir by holding more interstitial fluid • Macrophages and fat cells are contained in spaces © 2016 Pearson Education, Inc. Figure 4.8a Connective tissues. Connective tissue proper: loose connective tissue, areolar Description: Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells. Elastic fibers Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid. Ground substance Fibroblast nuclei Location: Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds capillaries. Epithelium Lamina propria © 2016 Pearson Education, Inc. Collagen fibers Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (340×). Types of Connective Tissues (cont.) • CT proper: loose connective tissues (cont.) – Adipose tissue • White fat – Similar to areolar tissue but greater nutrient storage – Cells are called adipocytes – Scanty matrix – Richly vascularized – Functions in shock absorption, insulation, and energy storage • Brown fat – Use lipid fuels to heat bloodstream rather than to produce ATP, as does white fat © 2016 Pearson Education, Inc. Figure 4.8b Connective tissues. Connective tissue proper: loose connective tissue, adipose Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet. Nucleus of adipose (fat) cell Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs. Fat droplet Location: Under skin in subcutaneous tissue; around kidneys and eyeballs; within abdomen; in breasts. Adipose tissue Mammary glands © 2016 Pearson Education, Inc. Photomicrograph: Adipose tissue from the subcutaneous layer under the skin (350×). Types of Connective Tissues (cont.) • CT proper: loose connective tissues (cont.) – Reticular connective tissue • Resembles areolar tissue, but fibers are thinner reticular fibers • Fibroblast cells are called reticular cells – Secrete reticular fibers made up of thin collagen • Reticular fibers form a mesh-like stroma that acts as a support for blood cells in lymph nodes, spleen, and bone marrow © 2016 Pearson Education, Inc. Figure 4.8c Connective tissues. Connective tissue proper: loose connective tissue, reticular Description: Loose network of reticular fibers in a gel-like ground substance; reticular cells lie on the network. Function: Fibers form a soft internal skeleton (stroma) that supports other cell types including white blood cells, mast cells, and macrophages. White blood cell (lymphocyte) Reticular fibers Location: Lymphoid organs (lymph nodes, bone marrow, and spleen). Photomicrograph: Dark-staining network of reticular connective tissue fibers forming the internal skeleton of the spleen (350×). Spleen © 2016 Pearson Education, Inc. Types of Connective Tissues (cont.) • CT proper: dense connective tissues – Three varieties of dense connective tissue • Dense regular • Dense irregular • Elastic © 2016 Pearson Education, Inc. Types of Connective Tissues (cont.) • CT proper: dense connective tissues (cont.) – Dense regular connective tissue • Very high tensile strength; can withstand high tension and stretching • Closely packed bundles of thick collagen fibers run parallel to direction of pull – Fibers appear as white structures » Great resistance to pulling – Fibers slightly wavy, so stretch a little • Fibroblasts manufacture collagen fibers and ground substance • Very few cells and ground substance, mostly fibers • Poorly vascularized • Example: tendons and ligaments © 2016 Pearson Education, Inc. Figure 4.8d Connective tissues. Connective tissue proper: dense connective tissue, dense regular Description: Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast. Collagen fibers Function: Attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction. Nuclei of fibroblasts Location: Tendons, most ligaments, aponeuroses. Shoulder joint Ligament Tendon © 2016 Pearson Education, Inc. Photomicrograph: Dense regular connective tissue from a tendon (430×). Types of Connective Tissues (cont.) • CT proper: dense connective tissues (cont.) – Dense irregular connective tissue • Same elements as dense regular, but bundles of collagen are thicker and irregularly arranged • Forms sheets rather than bundles • Resists tension from many directions • Found in: – Dermis – Fibrous joint capsules – Fibrous coverings of some organs © 2016 Pearson Education, Inc. Figure 4.8e Connective tissues. Connective tissue proper: dense connective tissue, dense irregular Description: Primarily irregularly arranged collagen fibers; some elastic fibers; fibroblast is the major cell type. Nuclei of fibroblasts Function: Withstands tension exerted in many directions; provides structural strength. Location: Fibrous capsules of organs and of joints; dermis of the skin; submucosa of digestive tract. Collagen fibers Shoulder joint Photomicrograph: Dense irregular connective tissue from the fibrous capsule of a joint (430×). Fibrous joint capsule © 2016 Pearson Education, Inc. Types of Connective Tissues (cont.) • CT proper: dense connective tissues (cont.) – Elastic connective tissue • Some ligaments are very elastic – Example: ligaments connecting adjacent vertebrae must be very elastic • Also found in walls of many large arteries – Arteries need to stretch when blood enters and recoil to push blood out © 2016 Pearson Education, Inc. Figure 4.8f Connective tissues. Connective tissue proper: dense connective tissue, elastic Description: Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allows tissue to recoil after stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration. Elastic fibers Location: Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes. Photomicrograph: Elastic connective tissue in the wall of the aorta (250×). Aorta Heart © 2016 Pearson Education, Inc. Types of Connective Tissues (cont.) • Cartilage – Matrix secreted from chondroblasts (during growth) and chondrocytes (adults) • Chondrocytes found in cavities called lacunae • 80% water, with packed collagen fibers and sugar proteins (chondroitin and hyaluronic acid) – Tough yet flexible material that lacks nerve fibers – Avascular: receives nutrients from membrane surrounding it (perichondrium) • Periochondrium gives rise to chondroblasts and chondrocytes © 2016 Pearson Education, Inc. Types of Connective Tissues (cont.) • Three types of cartilage: – Hyaline cartilage • Most abundant; “gristle” • Appears as shiny bluish glass • Found at tips of long bones, nose, trachea, larynx, and cartilage of the ribs – Elastic cartilage • Similar to hyaline but with more elastic fibers • Found in ears and epiglottis – Fibrocartilage • Properties between hyaline and dense regular tissue • Strong, so found in areas such as intervertebral discs and knee © 2016 Pearson Education, Inc. Figure 4.8g Connective tissues. Cartilage: hyaline Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Chondrocyte in lacuna Function: Supports and reinforces; serves as resilient cushion; resists compressive stress. Matrix Location: Forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx. Photomicrograph: Hyaline cartilage from a costal cartilage of a rib (470×). Costal cartilages © 2016 Pearson Education, Inc. Figure 4.8h Connective tissues. Cartilage: elastic Description: Similar to hyaline cartilage, but more elastic fibers in matrix. Chondrocyte in lacuna Function: Maintains the shape of a structure while allowing great flexibility. Matrix Location: Supports the external ear (pinna); epiglottis. Photomicrograph: Elastic cartilage from the human ear pinna; forms the flexible skeleton of the ear (800×). © 2016 Pearson Education, Inc. Figure 4.8i Connective tissues. Cartilage: fibrocartilage Description: Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate. Function: Tensile strength allows it to absorb compressive shock. Chondrocytes in lacunae Location: Intervertebral discs; pubic symphysis; discs of knee joint. Collagen fiber Intervertebral discs Photomicrograph: Fibrocartilage of an intervertebral disc (125×). Special staining produced the blue color seen. © 2016 Pearson Education, Inc. Clinical – Homeostatic Imbalance 4.2 • Avascular cartilage loses ability to divide as we age, so injuries heal slowly – Common in people with sports injuries • Later in life, cartilage can calcify or ossify (become bony), causing chondrocytes to die © 2016 Pearson Education, Inc. Types of Connective Tissues (cont.) • Bone – Also called osseous tissue – Supports and protects body structures – Stores fat and synthesizes blood cells in cavities – Has more collagen compared to cartilage – Has inorganic calcium salts – Osteoblasts produce matrix – Osteocytes maintain the matrix • Reside in cavities in matrix called lacunae – Osteons: individual structural units – Richly vascularized © 2016 Pearson Education, Inc. Figure 4.8j Connective tissues. Others: bone (osseous tissue) Description: Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized. Central canal Lacunae Function: Supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis). Lamella Location: Bones Photomicrograph: Cross-sectional view of bone (125×). © 2016 Pearson Education, Inc. Types of Connective Tissues (cont.) • Blood – Most atypical connective tissue because it is fluid • Consists of cells surrounded by matrix (plasma) – Red blood cells are most common cell type – Also contains white blood cells and platelets – Fibers are soluble proteins that precipitate during blood clotting – Functions in transport and in carrying nutrients, wastes, gases, and other substances © 2016 Pearson Education, Inc. Figure 4.8k Connective tissues. Connective tissue: blood Description: Red and white blood cells in a fluid matrix (plasma). Function: Transport respiratory gases, nutrients, wastes, and other substances. Red blood cells (erythrocytes) White blood cells: • Lymphocyte • Neutrophil Location: Contained within blood vessels. Plasma Photomicrograph: Smear of human blood (1670×); shows two white blood cells surrounded by red blood cells. © 2016 Pearson Education, Inc. 4.4 Muscle Tissue • Highly vascularized • Responsible for most types of movement – Muscle cells possess myofilaments made up of actin and myosin proteins that bring about contraction • Three types of muscle tissues: – Skeletal muscle – Cardiac muscle – Smooth muscle © 2016 Pearson Education, Inc. Skeletal Muscle • Skeletal muscle tissue – Attached to and causes movement of bones – Also called voluntary muscle • Skeletal muscles can be consciously controlled – Cells are called muscle fibers • Contain multiple nuclei • Appear striated or banded © 2016 Pearson Education, Inc. Figure 4.9a Muscle tissues. Skeletal muscle Description: Long, cylindrical, multinucleate cells; obvious striations. Part of muscle fiber (cell) Function: Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control. Nuclei Location: In skeletal muscles attached to bones or occasionally to skin. Striations Photomicrograph: Skeletal muscle (440×). Notice the obvious banding pattern and the fact that these large cells are multinucleate. © 2016 Pearson Education, Inc. Cardiac Muscle • Cardiac muscle tissue – Found only in walls of heart – Involuntary muscle – Like skeletal muscle, contains striations; but cells have only one nucleus – Cells can have many branches that join branches of other cardiac cells • Intercalated discs are special joints where cardiac cells are joined © 2016 Pearson Education, Inc. Figure 4.9b Muscle tissues. Cardiac muscle Description: Branching, striated, generally uninucleate cells that interdigitate at specialized junctions (intercalated discs). Intercalated discs Function: As it contracts, it propels blood into the circulation; involuntary control. Striations Nucleus Location: The walls of the heart. Photomicrograph: Cardiac muscle (475×); notice the striations, branching of cells, and the intercalated discs. © 2016 Pearson Education, Inc. Smooth Muscle • Smooth muscle tissue – Found mainly in walls of hollow organs (other than heart) – Involuntary muscle – Has no visible striations – Spindle-shaped cells with one nucleus © 2016 Pearson Education, Inc. Figure 4.9c Muscle tissues. Smooth muscle Description: Spindle-shaped (elongated) cells with central nuclei; no striations; cells arranged closely to form sheets. Nuclei Function: Propels substances or objects (foodstuffs, urine, a baby) along internal passageways; involuntary control. Location: Mostly in the walls of hollow organs. Smooth muscle cell Photomicrograph: Sheet of smooth muscle from the digestive tract (500×). © 2016 Pearson Education, Inc. 4.5 Nervous Tissue • Main component of nervous system (brain, spinal cord, nerves) – Regulates and controls body functions • Made up of two specialized cells: – Neurons: specialized nerve cells that generate and conduct nerve impulses – Supporting cells that support, insulate, and protect neurons © 2016 Pearson Education, Inc. Figure 4.10 Nervous tissue. Nervous tissue Description: Neurons are branching cells; cell processes that may be quite long extend from the nucleus-containing cell body; also contributing to nervous tissue are nonexcitable supporting cells. Neuron processes Cell body Nuclei of supporting cells Axon Dendrites Cell body of a neuron Function: Neurons transmit electrical signals from sensory receptors and to effectors (muscles and glands); supporting cells support and protect neurons. Neuron processes Location: Brain, spinal cord, and nerves. Photomicrograph: Neurons (350×) © 2016 Pearson Education, Inc. 4.6 Covering and Lining Membranes • Composed of at least two primary tissue types: an epithelium bound to underlying connective tissue proper layer • Three types – Cutaneous membranes – Mucous membranes – Serous membranes © 2016 Pearson Education, Inc. Cutaneous Membranes • Another name for skin • Keratinized stratified squamous epithelium (epidermis) attached to a thick layer of connective tissue (dermis) • Unlike other membranes, skin is a dry membrane © 2016 Pearson Education, Inc. Figure 4.11a Classes of membranes. Cutaneous membrane The cutaneous membrane (the skin) covers the body surface. Cutaneous membrane (skin) © 2016 Pearson Education, Inc. Mucous Membranes • Mucosa indicates location, not cell composition • Also called mucosae – Line body cavities that are open to the exterior (example: digestive, respiratory, urogenital tracts) • Moist membranes bathed by secretions (or urine) • Epithelial sheet lies over layer of loose connective tissue called lamina propria • May secrete mucus © 2016 Pearson Education, Inc. Figure 4.11b Classes of membranes. Mucous membranes Mucous membranes line body cavities that are open to the exterior. Mucosa of nasal cavity Mucosa of mouth Esophagus lining Mucosa of lung bronchi © 2016 Pearson Education, Inc. Serous Membranes • Also called serosae • Found in closed ventral body cavities • Constructed from simple squamous epithelium (called mesothelium) resting on thin areolar connective tissue • Parietal serosae line internal body cavity walls • Visceral serosae cover internal organs • Cavity between layers is filled with slippery serous fluid, so these are moist membranes • Special names given to show location: pleurae (lungs), pericardium (heart), peritoneum (abdomen) © 2016 Pearson Education, Inc. Figure 4.11c Classes of membranes. Serous membranes Serous membranes line body cavities that are closed to the exterior. Parietal pleura Visceral pleura Parietal Visceral pericardium pericardium © 2016 Pearson Education, Inc. Parietal peritoneum Visceral peritoneum 4.7 Tissue Repair • When the body’s barriers are compromised, the inflammatory and immune responses are activated • Repair starts very quickly • Repair is the function of the inflammatory process © 2016 Pearson Education, Inc. Steps in Tissue Repair • Repair can occur in two major ways: – Regeneration: same kind of tissue replaces destroyed tissue, so original function is restored – Fibrosis: connective tissue replaces destroyed tissue, and original function lost • Step 1: Inflammation sets stage – Release of inflammatory chemicals causes: • Dilation of blood vessels • Increase in blood vessel permeability – Clotting of blood occurs © 2016 Pearson Education, Inc. Figure 4.12-1 Tissue repair of a nonextensive skin wound: regeneration and fibrosis. Scab Blood clot in incised wound Epidermis Vein Inflammatory chemicals Migrating white blood cell Artery 1 Inflammation sets the stage: • Severed blood vessels bleed. • Inflammatory chemicals are released by injured tissue cells, mast cells, and others. • Local blood vessels become more permeable, allowing white blood cells, fluid, clotting proteins, and other plasma proteins to seep into the injured area. • Clotting occurs; surface exposed to air dries and forms a scab. © 2016 Pearson Education, Inc. Steps in Tissue Repair (cont.) • Step 2: Organization restores blood supply – Organization begins as the blood clot is replaced with granulation tissue (new capillaryenriched tissue) – Epithelium begins to regenerate – Fibroblasts produce collagen fibers to bridge the gap until regeneration is complete – Any debris in area is phagocytized © 2016 Pearson Education, Inc. Figure 4.12-2 Tissue repair of a nonextensive skin wound: regeneration and fibrosis. Regenerating epithelium Area of granulation tissue ingrowth Fibroblast Macrophage Budding capillary 2 Organization restores the blood supply: • The clot is replaced by granulation tissue, which restores the vascular supply. • Fibroblasts produce collagen fibers that bridge the gap. • Macrophages phagocytize dead and dying cells and other debris. • Surface epithelial cells multiply and migrate over the granulation tissue. © 2016 Pearson Education, Inc. Steps in Tissue Repair (cont.) • Step 3: Regeneration and fibrosis effect permanent repair – The scab detaches – Fibrous tissue matures – Epithelium thickens and begins to resemble adjacent tissue – Results in a fully regenerated epithelium with underlying scar tissue, which may or may not be visible © 2016 Pearson Education, Inc. Figure 4.12-3 Tissue repair of a nonextensive skin wound: regeneration and fibrosis. Regenerated epithelium Fibrosed area © 2016 Pearson Education, Inc. 3 Regeneration and fibrosis effect permanent repair: • The fibrosed area matures and contracts; the epithelium thickens. • A fully regenerated epithelium with an underlying area of scar tissue results. Regenerative Capacity of Different Tissues • Tissues that regenerate extremely well include: – Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, bloodforming tissue • Tissue with moderate regenerating capacity: – Smooth muscle and dense regular connective tissue © 2016 Pearson Education, Inc. Regenerative Capacity of Different Tissues (cont.) • Tissues with virtually no functional regenerative capacity: – Cardiac muscle and nervous tissue of brain and spinal cord – New research shows cell division does occur, and efforts are underway to coax them to regenerate better © 2016 Pearson Education, Inc. Clinical – Homeostatic Imbalance 4.3 • Scar tissue that forms in organs, particularly the heart, can severely impair the function of that organ – May cause the organ to lose volume capacity – May block substances from moving through organ – May interfere with ability of muscles to contract or may impair nerve transmissions © 2016 Pearson Education, Inc. Clinical – Homeostatic Imbalance 4.3 • Scar adhesions may cause organs to adhere to neighboring structures, preventing normal functions • Scarring can potentially cause progressive failure of the organ, particularly the heart © 2016 Pearson Education, Inc. Developmental Aspects of Tissues • Primary germ layers – Superficial to deep: ectoderm, mesoderm, and endoderm – Formed early in embryonic development – Specialize to form the four primary tissues • Nerve tissue arises from ectoderm • Muscle and connective tissues arise from mesoderm • Epithelial tissues arise from all three germ layers © 2016 Pearson Education, Inc. Developmental Aspects of Tissues • Tissues function well through youth and middle age if given adequate diet and circulation and if wounds and infections are minimal • As the body ages, epithelia thin, so they are more easily breached • Tissue repair is less efficient • Bone, muscle tissues, and nervous tissues begin to atrophy • DNA mutations increase cancer risk © 2016 Pearson Education, Inc. Figure 4.13 Embryonic germ layers and the primary tissue types they produce. 16-day-old embryo (dorsal surface view) Ectoderm Mesoderm Endoderm © 2016 Pearson Education, Inc. Epithelium (from all three germ layers) Muscle and connective tissue (mostly from mesoderm) Nervous tissue (from ectoderm) Inner lining of digestive system (from endoderm)